As expected, the Leonid meteor shower put on a rather respectable display this past November 19. One strong shower was seen from Europe, where rates of a couple of thousand meteors per hour were briefly attained; a second and weaker -- although still impressive -- shower was seen a few hours later from North America, which witnessed rates up to a few hundred meteors per hour. Had the moon not been near its full phase that morning, the observed rates would almost certainly have been significantly higher.

This brings to a close the current era of strong Leonid meteor showers, which has been around since about 1997. These recent Leonid showers were due to the return of Comet Tempel-Tuttle -- the Leonids' parent comet, which has brought with it extremely strong Leonid showers at times in the past -- in early 1998. With a period of 33 years, Comet Tempel-Tuttle will not be this way again until 2031, however because of gravitational pulls by the planets we will almost certainly not be seeing any strong Leonid showers around that time. Not until three returns from now -- in 2098 -- are the circumstances again favorable for producing strong meteor showers from the Leonids. Until then, we'll have to be content with the "normal" Leonid displays of approximately ten meteors per hour.

In the meantime, there are the various meteor showers that come every year, and while none of these are anywhere near as strong as the Leonids at their best, these showers can nevertheless make time spent out under the stars worthwhile. At least three of these "annual" showers can produce up to 60 to 100 meteors per hour, and several others can produce about half that.

One of the three strongest showers is the Geminid shower, which happens to peak this weekend. The shower's peak will take place on Friday night/Saturday morning, December 13-14, and especially after the moon sets around 2:00 A.M. sky-watchers should easily be able to see one or more meteors every minute. As their name implies, the Geminids appear to radiate from the constellation of Gemini, the twins, which is high overhead during the early morning hours of these chilly mid-December nights.

The parent "comet" for the Geminids is, in contrast to other known showers, actually an asteroid, an object about three miles across that was discovered in 1983 by the Infrared Astronomical Satellite (IRAS) spacecraft and which has since been named Phaethon. Phaethon orbits around the sun every 1.4 years and comes very close to the sun (13 million miles) each time it does so. Because of its association with the Geminids there is speculation that Phaethon may actually be an "extinct" comet, although so far no evidence of any cometary activity has ever been observed. Perhaps we might detect such activity during those occasions when Phaethon passes close to Earth; it will do so five years from now, in December 2007, when it will pass 11.3 million miles from us, and near the end of this century, in 2093, it will come to within 1.8 million miles of our planet.

Later this month, peaking on the nights of December 22 and 23, is another meteor shower, the Ursids (so named because they appear to radiate from the bowl of the Little Dipper, or Ursa Minor, the little bear). The Ursids are usually a pretty weak affair, normally producing only about ten meteors per hour -- a rate which will be even lower this year, since these are only a couple of nights after full moon. On rare occasions, however -- including in 1986 and also, according to at least one report, in 2000 -- brief outbursts of rates up to ten times higher have been seen. The Ursids are associated with Comet Tuttle, an object with an orbital period of 13 1/2 years; when this comet next returns, in 2008, it will pass 23 million miles from Earth and perhaps become bright enough to see with the unaided eye.

Just after the turn of the year comes another one of our strongest annual meteor showers, the Quadrantids (which take their name from the obscure and no-longer-recognized constellation of Quadrans Muralis, the Mural Quadrant, which was located southeast of the Big Dipper's handle). During the past few decades the Quadrantids have sometimes produced peak rates as high as 150 meteors per hour, however this peak is very brief and usually doesn't last more than a couple of hours. In 2003 the Quadrantids are expected to peak around 5:00 P.M. MST on January 3; this is the wrong time of night for North America, but sky-watchers in Europe and Asia may see a good display.

Among known meteor showers, the Quadrantids are unusual in that no parent comet has ever been conclusively identified. The most likely candidate for this is Comet Machholz 1, discovered as recently as 1986 (incidentally, by a good personal friend of this author), and which orbits the sun every 5 1/4 years. Although the respective orbits of the Quadrantids and Comet Machholz 1 are rather different, calculations have shown that, thanks to gravitational pulls from the planets, the orbits were much more similar to each other a few thousand years ago. Comet Machholz 1 returned at the beginning of this year, and will be next around in 2007, when it should be visible in ordinary backyard telescopes.

There are, of course, the various other meteor showers that come by each year, including the third strong shower, the Perseids, that appear each August. While the Leonids will probably be quiet for most of the rest of this century, there should continue to be plenty of meteor activity throughout all the intervening years to keep sky-watchers busy.